Earth boring drill



Sept. 27, 1955 E. e, BOICE 2,719,026

EARTH BORING DRILL Filed April 28,. 1952 2 SheetsSheet 1 Ely/ n 6. 5o/ce I INVENTOR. M

Sept. 27, 1955 E. G. BOICE 2,719,026

EARTH BORING DRILL.

Filed April 28, 1952 2 Sheets-Sheet 2 E/v/n 6. 50/66 INVENTOR.

A T TOH/VE VJ United States Patent EARTH BORING DRILL Elvin G. Boice, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex., a corporation of Texas Application April 28, 1952, Serial No. 284,803

3 Claims. (Cl. 255-302) This invention relates to new and useful improvements in an earth boring drill bit, and particularly to a combination rolling and scraping cutting bit.

Earth boring drill bits have been used in the past with a combination scraper and roller cutter but these previously used bits have been found unsatisfactory in many instances for various reasons, among which was a lack of support for the central or inside portion of the bit. This combination type of bit is primarily constructed for drilling through formations of varying hardness. As is well known, in the drilling of wells and the like some of the formations which are encountered are soft and sticky and others are hard and brittle. -By using this combination type bit, the bit is satisfactory for drilling through the various types of formation since the blade type scraping cutter is generally preferable for soft formations, while the rolling cutter type tooth cutter is better for the hard formations. Thus, in the soft and sticky formations the scraping cutter is primarily the only cutting means, while in the hard and brittle formations the rolling cutter is primarily the only cutting means. This results in an undue strain with possible vibrations, shearing or breakage of the various bits if the central portion of the scraping cutter and the roller cutter are not adequately supported.

Furthermore, in the prior devices of this type, the slush or mud has been supplied through passages at substantially the same velocity and amount with respect to both the drag blade and the roller cutter so that an excessive wear and abrasion resulted on the roller cutter.

It is therefore an object of this invention to provide a combination rolling and scraping cutting bit for earth bore drilling in which the scraping cutter and the rolling cutter are interconnected by a bridge element or con necting means, whereby their central or inner portions are adequately supported to prevent excessive wear or other damage thereto.

An important object of this invention is to provide in the combination bit of this invention, a pair of slush or mud passages, one serving the drag bit blade and the other one serving the roller cutter for cleaning the same, together with means for controlling the velocity of flow through the respective passages to provide the desired fluid streams from a single fluid source.

Another object of this invention is to a combination scraper and roller cutter bit having a bridge element therebetween, wherein a protective and cutting element is associated with the bridge element to protect said bridge element against wear from the well formation and at the same time to perform an auxiliary cutting action.

Other and further objects of this invention will become apparent when the following description is considered in connection with the accompanying drawings, wherein:

Figure 1 is a vertical view of the combination bit of this invention, partly in section and partly in elevation, illustrating the relationship of the scraping cutter and 2,719,026 Patented Sept. 27, 1955 the rolling cutter as well as the slush or mud passages supplying the slush or mud thereto,

Figure 2 is an elevational view of the connector means or bridge element of this invention, illustrating the shaft portion extending therefrom and the relative inclination of the connector means or bridge element with respect to the drag bit blade,

Figure 3 is a plan view looking at the bottom of the combination bit of this invention along line 3-3 of Figure 1, and illustrating the relationship of the various elements, as well as the slush passage for supplying slush to the drag bit blade,

Figure 4 is an elevational view looking at the combination bit along line 4-4 of Figure 1, and further illustrating the relationship of the various elements of this bit.

Referring now to Figure 1,. therein can be seen the combination bit of this invention generally designated by the letter A. This combination bit A is primarily intended for earth bore drilling, such as in the drilling of oil, gas and water wells, and the like. This drilling bit A includes the head 10 having the usual threaded box 11 at its upper end for connection with a conventional drill string. This head 10 has a downward or depending lug 12 to which is attached the scraping cutter or drag bit blade 14. This drag bit blade 14 is of usual construction and may be aflixed to the lug 12 by suitable means, such as welding. The blade 14 is substantially flat and is tapered inwardly at its lower portion 14a to form the relatively sharp cutting edge 140. The cutting face 14b has preferably mounted thereon various inserts 15, which may be of a hard wearing material, such as tungsten carbide and similar materials. These inserts 15 are suitably spaced to present a hard wearing surface in the drilling of the earth bore. The relatively sharp cutting edge 14c is inclined inwardly and upwardly toward the center of the bit so that the maximum penetration of the bit is along the outer periphery thereof.

Positioned substantially diametrically opposite from the depending lug 12 and the drag bit blade 14 is a depending leg 16. This depending leg 16 has a downwardly and inwardly inclined spindle 16a having a hollow bore 17 therein. This spindle 16a has suitable races for receiving the roller bearings 18 and 19, as well as the ball bearings 20. These bearings 18 and 19, as well as ball bearings 20, permit anti-friction support of the rolling cutter 21 which is mounted for rotation thereon.

The roller cutter 21 is illustrated as having two sets of substantially adjacent cutter teeth 21a and 21b, but, of course, the cutter 21 may be of any type construction. As best seen in Figure 1, the cutter teeth 21a and 21b do not extend entirely across the one-half of the bit or bore hole diameter, although the drag blade or scraper cutter 14 does extend across approximately one-half of the bit diameter and the inner portion thereof extends substantially to the center line of the bit A.

A bridge element or connector means 25 is formed integral with a cylindrical shaft 26 which extends into and is secured within the bore of the spindle 16a by weld metal 35 or similar means. The bridge element is formed with a lateral extension 27 which is adapted to be welded, or otherwise secured, to the inner portion of the blade 14 and thus the bridge element functions to span the space between the roller cutter and the blade. The bridge 25 is also provided with a downwardly extending projection 28 which has the lower edge shaped to form an auxiliary or supplemental blade. The auxiliary blade 28 together with the cutter 21 extend for substantially one-half of the bit diameter.

The auxiliary blade 28 serves to protect the bridge element 25 against wear from the well formation, for without the blade 28, the formation would be forced against 3 the bridge 25 during drilling so that it would be gradually worn away, thus destroying the support and connection between the roller cutter 21 and the drag blade 14 provided by the bridge 25. Additionally, the blade 28 performs an auxiliary cutting action near the center of the bit, thereby supplementing the cutting performed by the blade 14 and roller cutter 21. The inner edge 28a of the blade 28 is sufliciently close to the inner edge 14d of the blade 14 that any core tending to form therebetween will be so weak that it will disintegrate before causing any wear on the bridge element 25.

In the drilling operation with the combination bit of this type, it is desirable that the slush or drilling mud be supplied to the bit from a common source. It is also de sirable that the rate of flow and the quantity of drilling mud or slush being supplied to the cutter 21 is less than that being supplied to the drag bit blade 14. To accomplish this objective, a pair of slush passages 36 and 37 are utilized in the bit head 10. These passages 36 and 37 are of the dual velocity construction disclosed in the copending U. S. patent application, Serial No. 263,054, filed December 24, 1951, by Robert G. Peter and Elmer J. Volmert. Thus, the passage 36 is of conventional construction, being simply a hole or a tube through the head 10 which directs the slush to the blade 14. The passage 37, however, includes a sleeve 38 mounted in the head 10 by threads 39, or other equivalent means. A seal ring 40 may be provided below threads 39, if desired. Openings or orifices 42' are provided in the sleeve 38. As explained in detail in the copending application above referred to, the openings 42 are of lesser diameter than the passage 36 and also the passage 37, thereby reducing the volume slush passing therethrough from the upper part of the bit head 10. To reduce the velocity of the slush directed against the roller cutter 21 as well as the volume, the openings 42' are disposed substantially diametrically opposite from each other, whereby the streams from the openings 42 oppose each other as they enter the passage 37, thus dissipating the slush velocity in a churning action with the slush then passing downwardly through the passage 37 at a relatively slow velocity as compared to its velocity as it passes through the openings 42.

Thus, it can be seen that the drag blade 14 would be supplied with slush or mud from the same source as supplies the roller cutter 21, such mud to the cutter 21 being supplied at a lower velocity and in reduced volume as compared to the mud supplied to the blade 14, thereby preventing the wearing away or abrasion of the rolling cutter teeth and other parts thereof due to excessive wear under high velocity and large quantities of slush.

The foregoing disclosure and descn'ption of the invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed is:

1. An earth boring drill including a head, a downwardly depending lug thereon to which is attached a fiattened drag bit blade extending across substantially onehalf of the transverse diameter of said drill, a downwardly depending leg on said head provided with a downwardly and inwardly inclined spindle having a hollow bore therein longitudinally of said spindle and upon which spindle is mounted a frusto-conical roller cutter for rotation thereon, said leg being positioned substantially diametrically opposite said drag bit blade, said roller cutter occupying less than one-half of the transverse diameter of said drill thereby providing an unoccupied space between said roller cutter and said drag bit blade, a bridge element between said roller cutter and said drag bit blade having one portion thereof secured to said drag bit blade and secured atanother portion thereof to said spindle by a shaft secured in said spindle bore and to said depending leg whereby the formerly unoccupied space is bridged by said bridge element to provide a rigid support between said cutter and said blade.

2'. The bit as set forth in claim 1, wherein said bridge element is provided with an integral downwardly projecting cutting blade portion extending downwardly as far as the cutting edge on said drag bit blade and being coplanar therewith.

3. The bit as set forth in claim 1, wherein said head is provided with a pair of spaced, parallel, downwardly extending slush passages, one for supplying slush to said drag bit blade and the other for supplying slush to said roller cutter, the slush coming from a common source above said passages, the passage supplying slush to said drag bit blade being unobstructed, the passage supplying slush to said roller cutter being provided with a sleeve having therein a longitudinal bore of less diameter than the diameter of said drag bit blade slush passage, said bore communicating with said roller cutter at its lower end and with a pair oflateral diametrically disposed openings at its upper end for controlling the velocity and volume of the slush passing therethrough to said roller cutter.

References Cited in the file of this patent UNITED STATES PATENTS 1,879,127 Schlumpf Sept. 27, 1932 2,057,209 Schlumpf Oct. 13, 1936 2,320,136 Kammerer May 25, 1943 2,380,112 Kinnear July 10, 1945 

